EP3049450B1 - Use of modified water-soluble polymers as crosslinking auxiliary agents - Google Patents

Description

The invention relates to the use of modified water-soluble polymers as crosslinking aids, optionally in combination with film-forming polymers, epoxy components or other hardeners, for example for coating compositions or adhesives, such as fiber coating, paper coating or construction chemical products.

Water-soluble polymers, such as polyvinyl alcohols, find many uses, inter alia, as additives for coating agents or adhesives and in particular as a protective colloid for polymers based on ethylenically unsaturated monomers. However, the high water solubility of such polymers often has a negative impact on the water load of application products. To improve the water resistance, compositions containing water-soluble polymers have been applied, for example, in combination with curing agents or crosslinkers. Thus crosslinkers with isocyanate or aldehyde groups were used for the crosslinking of polyvinyl alcohol at room temperature. After crosslinking, the water resistance of the products is improved, but such crosslinkers are harmful to health, which makes their use higher safety measures required. In addition, crosslinking is usually incomplete so that harmful compounds can be released from the application products over long periods of time.

Epoxy-containing compounds are known as further crosslinking systems which, however, lead to crosslinking only at relatively high temperatures, for example above 100 ° C. However, in many applications, for example in construction applications, such as tile adhesive or leveling compounds, the crosslinking has to take place already at room temperature. For room-temperature crosslinking of compounds containing epoxy groups, amines may additionally be added. In this procedure, the water-soluble polymers are not adequately crosslinked and the wet strength of products made therefrom can not fully satisfy.

As crosslinkers epoxy resins are often recommended, especially for protective colloid-stabilized polymer powder, such as in the WO 2012/177448 , of the US 2012/0329909 , of the US 2012/0329908 , of the US 2012/0329907 or the WO 2010/086217 described. The EP 0721004 describes water-redispersible polymer powders comprising film-forming, functionalized polymers and reactive compounds, wherein the reactive compounds are suitable for crosslinking with the functionalized polymers. The US 2001/0024644 describes protective colloid-stabilized polymer powders whose base polymers contain epoxy monomer units. The EP 0896029 teaches crosslinkable polymer compositions based on water-insoluble polymers and water-soluble polymers, wherein at least one of the two polymers contains crosslinkable groups which can form covalent bonds with insoluble organic or inorganic solids.

The EP 0885246 discloses the use of water-soluble polymers based on 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and N-methylolacrylamide solution (NMA) as protective colloids for water-insoluble polymers. However, such protective colloids are prone to formaldehyde release, which is frowned upon for health reasons. In addition, protective colloids based on such monomers are not water resistant. The EP 0723975 describes the copolymerization of ethylenically unsaturated epoxides and other ethylenically unsaturated monomers in the presence of small amounts of protective colloids and the use of such products in coating compositions or binders to improve their adhesive properties. For film-forming polymers teaches the DE-A 102012223620 finally protective colloids, which are obtainable by polymerization of optionally functionalized ethylenically unsaturated monomers in the presence of water-soluble polymers.

Another problem is the inadequate resistance to fouling of the coatings outlined above, for example, contact with dye-containing beverages, e.g. Fruit juices or coffee.

Against this background, the task was to provide new measures for the production of water-resistant coatings as possible. Formaldehyde-releasing crosslinking aids should hereby be dispensed with. The crosslinking aids should also be crosslinkable without the addition of common crosslinkers, but if possible also be compatible with the common crosslinkers and crosslink in an advantageous manner under the influence of such common crosslinkers. In addition, the crosslinking aids should result in application products having improved soil resistance, for example to dye-containing beverages such as fruit juices or coffee, or to application products from which soils are more easily or completely removable. The problems mentioned above should, if possible, not occur or, if possible, to a lesser extent.

Surprisingly, this object has been achieved by using in a certain way modified water-soluble polymers as crosslinking aids.

1. a) einem oder mehreren ethylenisch ungesättigten Monomeren, die ein oder mehrere Epoxid-, Amin-, Carbonsäure-, Carbonsäureanhydrid- und/oder Silan-Gruppen tragen, und
2. b) einem oder mehreren, von den Monomeren a) verschiedenen ethylenisch ungesättigten Monomeren
   in Gegenwart von 25 bis 80 Gew.-% an einem oder mehreren wasserlöslichen Polymeren, bezogen auf das Gesamtgewicht der modifizierten wasserlöslichen Polymere.

The invention relates to the use of modified water-soluble polymers as crosslinking agents, characterized in that the modified water-soluble polymers are obtainable by free-radically initiated polymerization of

1. a) one or more ethylenically unsaturated monomers which carry one or more epoxide, amine, carboxylic acid, carboxylic anhydride and / or silane groups, and
2. b) one or more, different from the monomers a) ethylenically unsaturated monomers
   in the presence of from 25 to 80% by weight of one or more water-soluble polymers, based on the total weight of the modified water-soluble polymers.

The ethylenically unsaturated monomers which carry one or more epoxide, amine, carboxylic acid and / or carboxylic anhydride groups preferably have 1 to 20 C atoms, more preferably 1 to 10 C atoms, which are linear or branched, open-chain or cyclic could be. The amine-bearing ethylenically unsaturated monomers may be primary, secondary or tertiary amines.

Examples of ethylenically unsaturated monomers which carry one or more epoxide groups (epoxy-functional monomers) are glycidyl acrylate, glycidyl methacrylate (GMA) or allyl glycidyl ether; particularly preferred are glycidyl acrylate and glycidyl methacrylate; most preferred is glycidyl methacrylate.

Examples of ethylenically unsaturated monomers which carry one or more amine groups (amine-functional monomers) are 2-dimethylaminoethyl methacrylate, 2-tert. Butylaminoethyl methacrylate, allyl N- (2-aminoethyl) carbamate hydrochloride, allyl N- (6-aminohexyl) carbamate hydrochloride, allyl N- (3-aminoproparyl) hydrochloride, allylamine or vinylpyridine.

Examples of ethylenically unsaturated monomers which carry one or more carboxylic acid groups (carboxylic acid-functional monomers) are ethylenically unsaturated mono- or dicarboxylic acids, preferably acrylic acid, methacrylic acid, fumaric acid and maleic acid; Monoesters of fumaric acid or maleic acid, such as diethyl or diisopropyl esters. An example of an ethylenically unsaturated monomer bearing a carboxylic acid anhydride group (carboxylic acid anhydride functional monomer) is maleic anhydride.

Ethylenically unsaturated monomers which carry one or more silane groups (silane-functional monomers) are, for example, ethylenically unsaturated silicon compounds of the general formula R ¹ SiR ² _0-2 (OR ³ ) _1-3 , where R ^{1 is} CH ₂ = CR ⁴ - (CH ₂ ) _0-1 or CH ₂ = CR ⁴ CO ₂ (CH ₂ ) _1-3 , R ^{2 is} C ₁ - to C ₃ -alkyl, C ₁ - to C ₃ alkoxy or halogen, preferably Cl or Br, R ^{3 is} an unbranched or branched, optionally substituted alkyl radical having 1 to 12 C-atoms, preferably 1 to 3 C-atoms, or an acyl radical having 2 to 12 C atoms, wherein R ^{3 may} optionally be interrupted by an ether group, and R ^{4 is} H or CH ₃ .

Preferred silane-functional monomers are γ-acrylic or γ-methacryloxypropyltri (alkoxy) silanes, α-methacryloxymethyltri (-alkoxy) silanes, γ-methacryloxypropyl-methyldi (alkoxy) silanes; Vinylsilanes such as Vinylalkyldi (alkoxy) silanes and Vinylt-ri (alkoxy) silanes, wherein as alkoxy groups, for example, methoxy, ethoxy, methoxyethylene, ethoxyethylene, Methoxypropylenglykolether- or Ethoxypropylenglykolether residues can be used. Examples of preferred silane-containing monomers include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltris (1-methoxy) -isopropoxysilan, vinyltributoxysilane, vinyltriacetoxysilane, methacryloxymethyltrimethoxysilane, 3-methacryloxypropyl-tris (2- methoxyethoxy) Vinyltrichorsilan, vinylmethyldichlorosilane, vinyltris silane, (2-methoxyethoxy) silane, trisacetoxyvinylsilane, Allylvinyltrimethoxysilan, allyltriacetoxysilane, vinyldimethylmethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, vinyldimethylacetoxysilane, Vinylisobutyldimethoxysilan, Vinyltriisopropyloxysilan, vinyltributoxysilane, Vinyltrihexyloxysilan, Vinylmethoxydihexoxysilan, Vinyltrioctyloxysilan, Vinyldimethoxyoctyloxysilan, Vinylmethoxydioctyloxysilan, Vinylmethoxydilauryloxysilan, Vinyldimethoxylauryloxysilane and also Polyethylenglykolmodifi grained vinylsilane.

Most preferred as silane-functional monomers are vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyltris (1-methoxy) isopropoxysilane, methacryloxypropyltris (2-methoxyethoxy) silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane and methacryloxymethyltrimethoxysilane and mixtures thereof.

Suitable silane-functional monomers are also silane-containing (meth) acrylamides of the general formula CH ₂ = CR ⁵ -CO-NR ⁶ -R ⁷ -SiR ⁸ n- (R ⁹ ) _3-m , where n = 0 to 4, m = 0 to 2, R ^{5 is} either H or a methyl group, R ^{6 is} H or an alkyl group of 1 to 5 C atoms; R ^{7 is} an alkylene group having 1 to 5 C atoms or a bivalent organic group in which the carbon chain is interrupted by an O or N atom, R ^{8 is} an alkyl group having 1 to 5 C atoms, R ^{9 is} an alkoxy group having 1 to 40 carbon atoms, which may be substituted with other heterocycles. In monomers where 2 or more R ⁵ or R ⁹ groups are present, these may be identical or different.

Examples of such (meth) acrylamido-alkylsilanes are: 3- (meth) acrylamido-propyltrimethoxysilane, 3- (meth) acrylamido-propyltriethoxysilane, 3- (meth) acrylamido-propyltri (β-methoxyethoxy) silane, 2- (meth ) acrylamido-2-methylpropyltrimethoxy-silane, 2- (meth) acrylamido-2-methylethyltrimethoxysilane, N- (2- (meth) acrylamidoethyl) aminopropyltrimethoxysilane, 3- (meth) acrylamido-propyltriacetoxysilane, 2- (meth) acrylamido -ethyl-trimethoxysilane, 1- (meth) acrylamido-methyltrimethoxysilane, 3- (meth) acrylamido-propylmethyldimethoxysilane, 3- (meth) acrylamido-propyldimethylmethoxysilane, 3- (N-methyl- (meth) acrylamido) propyltrimethoxysilane , 3 - ((meth) acrylamido-methoxy) -3-hydroxypropyltrimethoxysilane, 3 - ((meth) acrylamido-methoxy) -propyltrimethoxysilane, N, N-dimethyl-N-trimethoxysilylpropyl-3- (meth) acrylamido-propylammonium chloride and NN- dimethyl-N-tri-methoxysilylpropyl-2- (meth) acrylamido-2-methylpropylammonium chloride.

The monomers a) are preferably in an amount of 0.5 to 60 wt .-%, particularly preferably 1 to 30 wt .-% and most preferably 2 to 20 wt .-%, each based on the total weight of the modified water-soluble polymers used.

Monomers b) are preferably selected from the group comprising vinyl esters, (meth) acrylic esters, vinylaromatics, olefins, 1,3-dienes and vinyl halides. Particularly preferred monomers b) are (meth) acrylic esters and vinylaromatics.

Suitable vinyl esters are, for example, those of carboxylic acids having 1 to 22 C atoms, in particular 1 to 12 C atoms. Preference is given to vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinylarachinate, 1-methylvinyl acetate, vinyl pivalate and vinyl esters of α-branched monocarboxylic acids having 9 to 11 C atoms, for example VeoVa9 ^R or VeoVa10 ^R (Trade name of the company Resolution). Particularly preferred is vinyl acetate.

Suitable acrylic esters or methacrylic esters are, for example, esters of unbranched or branched alcohols having 1 to 22 C atoms, in particular 1 to 15 C atoms. Preferred methacrylic esters or acrylic esters are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, 2-ethylhexyl acrylate, lauryl acrylate, myristyl acrylate, stearyl acrylate, palmityl acrylate, lauryl methacrylate, myristyl methacrylate, stearyl methacrylate or palmityl methacrylate. Particularly preferred are methyl acrylate, methyl methacrylate, n-butyl acrylate, t-butyl acrylate or 2-ethylhexyl acrylate.

Preferred vinyl aromatic compounds are styrene, methylstyrene and vinyltoluene. Preferred vinyl halide is vinyl chloride. The preferred olefins are ethylene, propylene, and the preferred dienes are 1,3-butadiene or isoprene.

The monomers b) are preferably used in an amount of 5 to 73 wt .-%, particularly preferably 10 to 65 wt .-% and most preferably 20 to 60 wt .-%, each based on the total weight of the modified water-soluble polymers ,

Optionally, one or more ethylenically unsaturated monomers c) different from the monomers a) and b) can be used in the free-radically initiated polymerization to prepare the modified water-soluble polymers.

Examples of monomers c) are ethylenically unsaturated carboxylic acid amides and nitrites, preferably acrylamide and acrylonitrile; Diesters of fumaric acid and maleic acid, such as the diethyl and diisopropyl esters, ethylenically unsaturated sulfonic acids or salts thereof, preferably vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid. Further examples are precrosslinking comonomers such as multiply ethylenically unsaturated comonomers, for example diallyl phthalate, divinyl adipate, diallyl maleate, allyl methacrylate or triallyl cyanurate, or post-crosslinking comonomers, for example acrylamidoglycolic acid (AGA), methyl acrylamidoglycolic acid methyl ester (MAGME), N-methylolacrylamide (NMA), N-methylol methacrylamide, N- Methylolallyl carbamate, alkyl ethers such as the isobutoxy ether or esters of N-methylolacrylamide, N-methylolmethacrylamide and N-methylolallylcarbamate. Mention may also be made of monomers having hydroxyl or CO groups, for example methacrylic acid and acrylic acid hydroxyalkyl esters such as hydroxyethyl, hydroxypropyl or hydroxybutyl acrylate or methacrylate, and also compounds such as diacetoneacrylamide or acetylacetoxyethyl acrylate or methacrylate.

The monomers c) are preferably used at 0.1 to 10 wt .-% and particularly preferably 0.1 to 5 wt .-%, each based on the total weight of the modified water-soluble polymers. Most preferably, no monomers c) are used.

The water-soluble polymers generally have a solubility of at least 10 g / l in water at a temperature between 20 ° C. and 90 ° C. and a pH of between 3 and 12, in particular at a pH of between 3 and 9.

Suitable water-soluble polymers are, for example, polymers comprising units of vinyl alcohol, vinylpyrrolidones, vinyl acetals, ethylenically unsaturated carboxylic acids, acrylamides, vinylsulfonic acids, ethylenically unsaturated amines or ammonium compounds or else polymers such as polysaccharides in water-soluble form, proteins, lignosulfonates or formaldehyde sulfonates.

Preferred water-soluble polymers are polyvinyl alcohols; polyvinyl; polyvinylpyrrolidones; Polysaccharides in water-soluble form such as starches (amylose and amylopectin), celluloses and their carboxymethyl, methyl, hydroxyethyl, hydroxypropyl derivatives, dextrins and cyclodextrins; Proteins such as casein or caseinate, soy protein, gelatin; lignin; synthetic polymers such as poly (meth) acrylic acid, copolymers of (meth) acrylates with carboxyl-functional comonomer units, poly (meth) acrylamide, polyvinylsulfonic acids and their water-soluble copolymers; Melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates, cresol formaldehyde sulfonates, styrene maleic acid and vinyl ether maleic acid copolymers.

Preferred polyvinyl alcohols are also polyvinyl alcohols containing hydrophobic monomer units, for example saponified copolymers of vinyl acetate with hydrophobic comonomers such as isopropenyl acetate, vinyl pivalate, vinyl ethyl hexanoate, vinyl esters of saturated alpha-branched monocarboxylic acids having 5 or 9 to 11 carbon atoms, dialkyl maleates and dialkyl fumarates such as diisopropyl maleate and diisopropyl fumarate, vinyl chloride , Vinyl alkyl ethers such as vinyl butyl ether, olefins such as ethene and decene. The proportion of the hydrophobic monomer units is preferably 0.1 to 10 wt .-%, based on the total weight of the respective polyvinyl alcohol.

The polyvinyl alcohols may also be cationic polyvinyl alcohols or anionic polyvinyl alcohols. Cationic protective colloids are polymers with cationic charge; anionic protective colloids are polymers with anionic charge.

Examples of cationic polyvinyl alcohols are polymers containing cationic monomer units, preferably monomer units with quaternary ammonium groups, sulfonium groups and phosphonium groups. Saponified copolymers of vinyl acetate with one or more cationic comonomers are preferably selected from the group comprising allyl-alkyl-ammonium halides, (meth) acryloxy-alkyl-ammonium halides, (meth) acrylamido-alkyl-ammonium halides, amino-alkyl (meth) acrylate and Amino-alkyl (meth) acrylamide, wherein the alkyl radicals may contain 1 to 4 carbon atoms. Preferred cationic comonomers are selected from the group comprising diallyl diethylammonium chloride (DADEAC), (3-methacryloxy) propyltrimethylammonium chloride (MPTAC), (3-methacryloxy) ethyltrimethylammonium chloride (METAC), (3-methacrylamido) propyltrimethylammonium chloride (MAPTAC), 2-dimethylaminoethyl methacrylate or 3-dimethylaminopropylmethacrylamide (DMAEMA or DMAPMA at pH ≤ 5 protonated species) and in particular diallyldimethylammonium chloride (DADMAC). Most preferred monomers c) are diallyldimethylammonium chloride (DADMAC), diallyldi-ethylammonium chloride (DADEAC), (3-methacryloxy) propyltrimethylammonium chloride (MPTAC), (3-methacryloxy) ethyltrimethylammonium chloride (METAC), (3-methacrylamido) propyltrimethylammonium chloride ( MAPTAC). The preparation of cationic polyvinyl alcohols is for example in the EP1724288A1 or in EW Flick, Water-Soluble Resins - An Industrial Guide, Noyes Publications, Park Ridge, NJ, 1991 described.

The proportion of the cationic comonomers is preferably 0.01 to 30 wt .-%, particularly preferably 1 to 15 wt .-%, more preferably 1 to 10 wt .-% and most preferably 1 to 5 wt .-%, respectively based on the total weight of the cationic polyvinyl alcohols.

Examples of anionic polyvinyl alcohols are polymers containing anionic monomer units, preferably monomer units having sulfate, sulfonic acid, phosphate, phosphonate and carboxylic acid groups or their respective salts. Especially Preferred anionic monomer units carry phosphate, phosphonate or especially sulfonic acid or carboxylic acid groups. Saponified copolymers of vinyl acetate with one or more anionic comonomers are preferably selected from the group comprising vinyl sulfonates, allyl sulfonates, ethylenically unsaturated mono- or dicarboxylic acids, monoesters of fumaric acid and maleic acid. Particularly preferred are vinyl sulfonates and ethylenically unsaturated mono- or dicarboxylic acids. Particularly preferred are vinylsulfonate, 2-methyl-2-propene-1-sulfonic acid, allylsulfonate, acrylic acid, methacrylic acid, fumaric acid, maleic acid, monoethyl or Monoisopropylester of fumaric acid or maleic acid, or the salts of the aforementioned acids. Most preferred is vinyl sulfonate. The preparation of anionic polyvinyl alcohols is for example in the WO06122705A described.

The proportion of the anionic comonomers is preferably 0.01 to 30 wt .-%, particularly preferably 1 to 20 wt .-%, more preferably 1 to 15 wt .-% and most preferably 1 to 10 wt .-%, respectively based on the total weight of the anionic polyvinyl alcohols.

Preference is given to partially hydrolyzed or fully hydrolysed polyvinyl alcohols having a degree of hydrolysis of from 80 to 100 mol%, in particular partially hydrolyzed polyvinyl alcohols having a degree of hydrolysis of from 80 to 95 mol%. The degree of hydrolysis denotes the molar ratio of the vinyl alcohol units and the total of the vinyl alcohol and vinyl ester units of the respective water-soluble polymer.

The polyvinyl alcohols have a Höppler viscosity of preferably 0.4 to 30 mPas, more preferably 0.4 to 15 mPas, more preferably from 0.5 to 10 mPas and most preferably from 0.8 to 6 mPas (determined by the method according to Höppler at 20 ° C according to DIN 53015 in 4% aqueous solution).

Polyvinyl acetals are obtainable by partial or complete acetalization of the partially or completely hydrolyzed polyvinyl alcohols. The preparation of the polyvinyl acetals is carried out by conventional methods by acetalization of said polyvinyl alcohols with aldehydes, such as in the DE-A 10140131 described. Preference is given to aldehydes from the group of aliphatic aldehydes having 1 to 15 C atoms, in particular formaldehyde, acetaldehyde, propionaldehyde and most preferably butyraldehyde or a mixture of butyraldehyde and acetaldehyde. As aromatic aldehydes, for example, benzaldehyde or its derivatives can be used. The degree of acetalization of the polyvinyl acetals can be adjusted by the amount of aldehyde used. Because the acetalization proceeds with almost complete conversion, the added amount can be determined by simple stoichiometric calculation.

Particularly preferred water-soluble polymers are polyvinyl alcohols, in particular cationic polyvinyl alcohols or anionic polyvinyl alcohols.

For the preparation of the modified water-soluble polymers by means of polymerization, the water-soluble polymers are preferably from 25 to 80% by weight, more preferably from 30 to 70% by weight and most preferably from 35 to 60% by weight, based in each case on the total weight of the modified water-soluble polymers used.

In the course of the polymerization for the preparation of the modified water-soluble polymers, monomer units of the monomers a) and / or of the monomers b) and / or optionally of the monomers c) are generally grafted onto the water-soluble polymers. Grafting means that units of the ethylenically unsaturated monomers are attached to the water-soluble polymers via covalent bonds.

The polymer units based on the monomers a), b) and optionally c) of the modified, water-soluble polymers have volume-average particle sizes of preferably 10 nm to 200 nm, more preferably from 30 nm to 180 nm and most preferably from 40 nm to 130 nm (determination by means of BeckmanCoulter LS 13320 (PIDS)). These particle sizes are particularly advantageous in terms of the increased adhesion of crosslinked modified water-soluble polymers to substrates.

The modified water-soluble polymers can be prepared, for example, by emulsion polymerization of the ethylenically unsaturated monomers of the invention in the presence of one or more water-soluble polymers. Preferably, therefore, no suspension polymerization takes place. The polymerization temperature is preferably between 40 ° C and 100 ° C, more preferably between 60 ° C and 90 ° C. In the copolymerization of gaseous comonomers such as ethylene, 1,3-butadiene or vinyl chloride, it is also possible to work under pressure, generally between 5 bar and 100 bar. The pH during the polymerization is preferably between 2 and 11. When monomers a) carrying epoxy groups are used, the pH during the polymerization is preferably between 4 and 9, more preferably between 4 and 8, and most preferably between 6 and 7. The pH can be adjusted in a known manner by organic and inorganic acids, bases or buffers, such as by addition of hydrochloric acid, ammonia or alkaline earth or alkali metal hydroxides, such as sodium hydroxide.

The polymerization is usually carried out in water, optionally mixed with one or more organic solvents, such as alcohols having 1 to 7 carbon atoms. Examples of alcohols are methanol, ethanol, propanol, butanol or pentanol. The proportion of water, based on the total weight of the organic solvents and water, is preferably ≥ 50% by weight, more preferably ≥ 90% by weight and most preferably 100% by weight.

To initiate the polymerization, it is possible to use, for example, the monomer-soluble initiators customary for emulsion polymerization, in particular water-soluble initiators or also redox initiator combinations; preferably is dispensed with redox initiator combinations. Examples of water-soluble initiators are hydrogen peroxide, t-butyl peroxide, t-butyl hydroperoxide, potassium peroxodiphosphate, tert-butyl peroxopivalate, cumene hydroperoxide, isopropylbenzene monohydroperoxide, azobisisobutyronitrile. Examples of monomer-soluble initiators are dicetyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, dibenzoyl peroxide or, preferably, (alkaline) alkali metal or ammonium salts, such as sodium, potassium and ammonium salts, peroxodisulfuric acid.

The water resistance of the modified water-soluble polymers or their application products can be further increased in particular by using peroxodisulfuric acid or its salts as initiator.

The initiators mentioned are generally used in an amount of 0.1 to 5.0 wt .-%, preferably 0.2 to 2.0 wt .-%, each based on the total weight of the monomers.

Preferably, ≥20% by weight, more preferably ≥30% by weight, more preferably ≥40% by weight and even more preferably ≥50% by weight of the initiators are initially charged and the remaining portion of the initiators is metered in during the polymerization, based on the total weight of the initiators. During the polymerization, preferably ≦ 80% by weight, more preferably ≦ 60% by weight and even more preferably ≦ 10% by weight of the initiators are metered in, based on the total weight of the initiators. Most preferably, no initiators are added during the polymerization or the initiators are completely charged. After complete addition of the monomers but additional amounts of initiators can be added for post-polymerization. Also by the inventive template or dosage of the initiators, the water resistance of the modified water-soluble polymers or their application products can be improved. In addition, the particle size or the viscosity of the modified water-soluble polymers can be controlled in this way.

Combinations of the stated initiators and reducing agents can be used as redox initiators. Suitable reducing agents are, for example, the sulfites and bisulfites of the alkali metals and of ammonium, such as sodium sulfite, the derivatives of sulfoxylic acid, such as zinc or alkali metal formaldehyde sulfoxylates, such as sodium hydroxymethanesulfinate, and ascorbic acid. The amount of reducing agent is generally from 0.001 to 0.03 wt .-%, preferably 0.001 to 0.015 wt .-%, each based on the total weight of the monomers.

The water-soluble polymers can be completely or partially metered or preferably completely charged. Preferably, at least 50% by weight, more preferably at least 60% by weight and most preferably at least 80% by weight, of the water-soluble polymers are initially charged, based in each case on the total amount of water-soluble polymers used.

Preferably, ≥50 wt%, more preferably ≥60 wt%, even more preferably ≥70 wt%, and most preferably ≥80 wt% of the total amount of water-soluble polymers used is initially charged or metered , to which ≤ 60 wt .-%, preferably ≤ 50 wt .-%, more preferably ≤ 40 wt .-% and most preferably ≤ 30 wt .-% of the total amounts of monomers used a) and b) initially charged or added are.

The monomers a) and b) can be initially charged in total or, in particular, completely metered in. The monomers a) and b) are preferably added to 0 to 20 wt .-%, in particular 0 to 10 wt .-%, based on the total weight of the total amounts of monomers used a) and b), and the remaining amount of the Monomers a) and b) are metered in at a later time during the polymerization, in particular at a point in time of ≥ 50% by weight, preferably ≥ 60% by weight, more preferably ≥ 70% by weight and most preferably ≥ 80% by weight of the total amount of water-soluble polymer used is charged or added. The dosages can be carried out separately (spatially and temporally).

The preferred dosage or template of the monomers b) and in particular the monomers a) or the water-soluble polymers are particularly useful for improving the crosslinking properties of the modified water-soluble polymers or to increase the water resistance of their application products.

During the polymerization, additional emulsifiers may be present. If the polymerization is carried out in the presence of emulsifiers, the amount thereof is preferably from 1 to 5% by weight, based on the weight of the monomers a) and b). Preferably, polymerization is carried out in the absence of emulsifiers. Examples of emulsifiers are anionic, cationic, amphoteric, polymerizable or nonionic emulsifiers, such as anionic surfactants, in particular alkyl sulfates having a chain length of 8 to 18 carbon atoms, alkyl or alkylaryl ether sulfates having 8 to 18 carbon atoms in the hydrophobic radical and up to 40 Ethylene or propylene oxide units, alkyl or alkylaryl sulfonates having 8 to 18 carbon atoms, esters and half esters of sulfosuccinic acid with monohydric alcohols or alkylphenols, or nonionic surfactants such as alkyl polyglycol ethers or alkylaryl polyglycol ethers having 8 to 40 ethylene oxide units.

For controlling the molecular weight or the viscosity, regulating substances can be used during the polymerization. If regulators are used, these are usually used in amounts of from 0.01 to 5.0% by weight, based on the monomers a) to be polymerized and optionally b), and metered in separately or else premixed with reaction components. Examples of such substances are n-dodecylmercaptan, tert-dodecylmercaptan, mercaptopropionic acid, methyl mercaptopropionate, isopropanol and acetaldehyde.

The modified water-soluble polymers are preferably in water or in a mixture of water and organic Solvent, in particular with a solids content of 5% to 60%, preferably 10% to 50% and particularly preferably 15% to 45%. The viscosities of the modified water-soluble polymers depend very much on which water-soluble polymers were used for their preparation, so that modified water-soluble polymers having a wide variety of viscosities are accessible.

Aqueous dispersions or aqueous solutions of the modified water-soluble polymers are characterized by a high stability. This manifests itself, for example, in that the modified water-soluble polymers in aqueous form can not be separated into a polymer phase and a serum during one hour centrifugation by means of an ultracentrifuge (Optimal L-100k from Beckman Coulter) under normal conditions according to DIN50014 at 40,000 revolutions per minute. in contrast to the known protective colloid-stabilized polymers of ethylenically unsaturated monomers.

To prepare the modified water-soluble polymers in the form of solids, in particular in the form of powders, modified water-soluble polymers in the form of dispersions or solutions can be freed of water and optionally solvent in a known manner, for example by means of precipitation, distillation or drying, in particular by fluidized-bed drying, Freeze drying or spray drying. The drying of the modified water-soluble polymers is preferably carried out without the addition of drying aids, that is preferably without the above water-soluble polymers are added after completion of the polymerization to prepare the modified water-soluble polymers, and in particular without the water-soluble polymers are added during drying. Preferably, the dispersions are spray-dried. The spray drying is carried out in conventional spray drying systems, wherein the atomization can be done by means of one-, two- or multi-fluid nozzles or with a rotating disk. The exit temperature is generally in the range of 45 ° C to 120 ° C, preferably 60 ° C to 90 ° C chosen.

In this way, modified water-soluble polymers can be obtained in the form of water-dilutable or water-redispersible powders.

To increase the shelf life by improving the blocking stability, the powder obtained can be equipped with antiblocking agent (anti-caking agent). Preferably, the modified water-soluble polymers in the form of powders contain from 2 to 10% by weight of antiblocking agent, based on the dry weight of the modified water-soluble polymers. However, it is particularly preferable to dispense with the addition of antiblocking agent. Examples of antiblocking agents are Ca or Mg carbonate, talc, gypsum, silicic acid, kaolins, metakaolin, calcined kaolin, silicates having particle sizes preferably in the range from 10 nm to 100 μm.

In a preferred embodiment, one or more modified water-soluble polymers are present as part of a crosslinking agent composition which additionally contains one or more components from the group comprising base polymers, epoxide components, hardeners and additives.

To prepare the crosslinker composition, the modified water-soluble polymers and the other component of the crosslinker composition may be mixed in a manner common in the art.

The base polymers are based on one or more ethylenically unsaturated monomers, for example selected from the group comprising the abovementioned monomers a), b) and c), wherein the same monomers are preferred, particularly preferred and most preferred, as indicated above. Such base polymers are also known as film-forming polymers.

Examples of homopolymers or copolymers which are suitable as base polymers are vinyl acetate homopolymers, copolymers of vinyl acetate with ethylene, copolymers of vinyl acetate with ethylene and one or more further vinyl esters, copolymers of vinyl acetate with ethylene and acrylic esters, copolymers of vinyl acetate with ethylene and vinyl chloride, styrene Acrylic acid ester copolymers, styrene-1,3-butadiene copolymers.

Preference is given to vinyl acetate homopolymers; Copolymers of vinyl acetate with from 1 to 40% by weight of ethylene; Copolymers of vinyl acetate with 1 to 40 wt .-% of ethylene and 1 to 50 wt .-% of one or more other comonomers from the group of vinyl esters having 1 to 12 carbon atoms in the carboxylic acid radical such as vinyl propionate, vinyl laurate, vinyl esters of alpha-branched Carboxylic acids having 5 to 13 C atoms, such as VeoVa9R, Veo-Va10R, VeoVa11R; Copolymers of vinyl acetate, 1 to 40% by weight of ethylene and preferably 1 to 60% by weight of acrylic esters of unbranched or branched alcohols having 1 to 15 C atoms, in particular n-butyl acrylate or 2-ethylhexyl acrylate; and copolymers having 30 to 75 wt .-% vinyl acetate, 1 to 30 wt .-% vinyl laurate or vinyl ester of an alpha-branched carboxylic acid having 5 to 13 carbon atoms, and 1 to 30 wt .-% acrylic acid esters of unbranched or branched alcohols 1 to 15 carbon atoms, in particular n-butyl acrylate or 2-ethylhexyl acrylate, which may still contain from 1 to 40% by weight of ethylene; Copolymers with vinyl acetate, 1 to 40% by weight of ethylene and 1 to 60% by weight of vinyl chloride; wherein the polymers may each still contain the said auxiliary monomers in the stated amounts, and the information in wt .-% add up to each 100 wt .-%.

Also preferred are (meth) acrylic acid ester polymers, such as copolymers of n-butyl acrylate or 2-ethylhexyl acrylate or copolymers of methyl methacrylate with n-butyl acrylate and / or 2-ethylhexyl acrylate and optionally ethylene; Styrene-acrylic acid ester copolymers with one or more monomers from the group of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate; Vinyl acetate-acrylic acid ester copolymers with one or more monomers from the group of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and optionally ethylene; Styrene-1,3-butadiene copolymers; wherein the polymers can still contain the said auxiliary monomers in the stated amounts, and the data in wt .-% add up to each 100 wt .-%.

The monomer selection or the selection of the proportions by weight of the comonomers is carried out so that in general a glass transition temperature Tg of -50 ° C to + 50 ° C, preferably -30 ° C to + 40 ° C results. The glass transition temperature Tg of the polymers can be determined in a known manner by means of differential scanning calorimetry (DSC). The Tg can also be approximated by the Fox equation. To Fox TG, Bull. Physics Soc. 1, 3, page 123 (1956 ): 1 / Tg = x1 / Tg1 + x2 / Tg2 + ... + xn / Tgn, where xn is the mass fraction (wt% / 100) of the monomer n, and Tgn is the glass transition temperature in Kelvin of the homopolymer of Monomers n is. Tg values for homopolymers are in Polymer Handbook 2nd Edition, J. Wiley & Sons, New York (1975 ).

The preparation of the base polymers can be carried out by means of free-radically initiated polymerization of the ethylenically unsaturated monomers, as described, for example, in US Pat DE-A 102006050336 described, preferably by emulsion polymerization in aqueous medium.

The base polymers may for example be stabilized emulsifier or preferably protective colloid stabilized. Protective colloids which may be used are, for example, the abovementioned water-soluble polymers or the modified water-soluble polymers according to the invention. Suitable emulsifiers are exemplified above. The emulsion polymerization processes for the preparation of the base polymers are preferably carried out in the presence of protective colloids, more preferably in the absence of the modified water-soluble polymers. In protective colloid-stabilized Base polymers, the protective colloids and the base polymers generally coexist.

The base polymers are generally obtained in the form of aqueous dispersions during the polymerization. To prepare the base polymers in the form of water-redispersible powders, the aqueous dispersions are dried, if appropriate after the addition of drying aids, for example the abovementioned water-soluble polymers, preferably the modified water-soluble polymers. In this case, the methods described above for the drying of the modified water-soluble polymers can be used. As a rule, the drying aid is used in a total amount of from 3 to 30% by weight, based on the polymeric constituents of the dispersion. Preference is given to using from 5 to 20% by weight, based on the polymer fraction.

Preference is also the use of polymer blends as crosslinking aids. Polymer blends contain one or more modified water-soluble polymers and one or more base polymers, especially one or more protective colloid-stabilized base polymers. Preferred polymer blends preferably contain from 2 to 95 wt%, more preferably from 5 to 50 wt%, and most preferably from 5 to 30 wt% of modified water-soluble polymers, based on the dry weight of the polymer blend. Preferred polymer blends also preferably contain from 5 to 98 weight percent, more preferably from 50 to 95 weight percent, and most preferably from 70 to 95 weight percent of protective colloid-stabilized base polymers, based on the dry weight of the polymer blend , The polymer blends are preferably in the form of aqueous dispersions and more preferably in the form of water-redispersible powders.

The introduction of the modified water-soluble polymers in the polymer blends can be done in different ways. For example, protective colloid-stabilized base polymers and modified water-soluble polymers, respectively be mixed in solid form or in each case in aqueous form. Furthermore, it is also possible to use either the protective colloid-stabilized base polymers or the modified water-soluble polymers in solid form and the other of the two components mentioned in aqueous form for mixing. Preferably, the modified water-soluble polymers, especially in the form of their aqueous form, are added before and / or during the drying of the aqueous protective colloid-stabilized base polymer dispersions.

Epoxy components are, for example, synthetic resins which carry epoxide groups, generally polyethers having at least two epoxide groups, in particular two terminal epoxide groups. Epoxy components are commonly polycondensates, in particular of polyhydric, monomeric alcohols and chlorine and epoxy groups-carrying monomers. The epoxy compounds may be aliphatic, araliphatic or aromatic in nature. The epoxy components preferably do not bear free-radically polymerizable groups, such as ethylenically unsaturated groups. Examples are bisphenol A type epoxide compounds, that is, condensation products of bisphenol A and epichlorohydrin or methylepichlorohydrin. Epoxy components based on bisphenol F, which generally contain a mixture of bisglycidyloxyphenylmethanes, are also suitable. Further examples are aliphatic epoxide compounds such as glycidyl ethers of aliphatic polyols, in particular the butyl diglycidyl ether or the trimethylolpropane triglycidyl ether; cycloaliphatic epoxy resins such as vinylcyclohexanedioxide, dicyclopentadiene dioxide and 3,4-epoxy-6-methylcyclohexylmethyl; and heterocyclic epoxy compounds such as triglycidyl isocyanurate. Such epoxy resins are commercially available, for example the bisphenol A and bisphenol F types as Epilox ^R resins. The bisphenol A-type and bisphenol-F-type epoxy resins are preferred, and glycidyl ethers of aliphatic polyols are particularly preferred.

The epoxy components are used in an amount of preferably 2 to 70% by weight, more preferably 4 to 50% by weight, respectively based on the dry weight of the modified water-soluble polymers used.

Preference is also the use of blends with epoxy components as crosslinking aids. Such blends contain one or more modified water-soluble polymers, one or more epoxy components, and optionally one or more base polymers, especially one or more protective colloid-stabilized base polymers. Preferred blends with epoxy components preferably contain from 5 to 70 wt%, more preferably from 5 to 50 wt%, and most preferably from 10 to 50 wt% of modified water-soluble polymers; preferably 5 to 90% by weight, more preferably 5 to 70% by weight, and most preferably 10 to 70% by weight of epoxy components; optionally 0 to 95 wt .-% and preferably 5 to 90 wt .-% of protective colloid-stabilized base polymers, wherein the data in wt .-% depending on the dry weight of the blends with epoxy components and total of 100 wt. - Add up%. The blends with epoxy components are preferably in the form of aqueous dispersions and more preferably in the form of water-redispersible powders.

To prepare the blends with epoxy components their individual components can be mixed in different ways. For example, the epoxide components, the modified water-soluble polymers and optionally the base polymers can each be used in solid form or in aqueous form for mixing. Furthermore, it is also possible that one or more components of a blend with epoxy components in solid form and remaining components in aqueous form are used for mixing. The epoxy components are preferably used as pure substance. The modified water-soluble polymers and / or the epoxide components are preferably mixed after preparation of the base polymers by means of polymerization and more preferably before and / or during the drying of the aqueous base polymer dispersions.

Hardeners accelerate crosslinking of the modified water-soluble polymers and / or optional epoxide components and allow crosslinking at higher cure rates, even at lower temperatures. Preferred hardeners are selected from the group comprising amines and silanes, in particular aminosilanes or epoxysilanes.

Preferred amines are those having two or more amino groups, for example aliphatic polyamines, polyoxyalkyleneamines, polyethyleneimines, aminosilanes and their condensation products, amino-functional polyvinyl alcohols. Particularly preferred amines are aliphatic polyamines, which are available under the trade names Anquamine ^R or Epilink ^R or Epilox ^R hardener, or polyoxyalkylene amines, which are available under the trade names Jeffamine ^R , or polyethyleneimines, which are available under the trade name polyimine.

Also preferred are aminosilanes and their condensation products. Suitable aminosilanes are, for example, those available under the trade name Geniosil ^R , such as N- (2-aminoethyl) (3-aminopropyl) trimethoxysilane (Geniosil GF 91), (3-aminopropyl) triethoxysilane (Geniosil GF 93), N- (2- Aminoethyl) (3-aminopropyl) methyldimethoxysilane (Geniosil GF 95).

Preferred epoxysilanes are 3-glycidoxypropyl) trimethoxysilane and in particular (3-glycidoxypropyl) triethoxysilane.

The hardener blends are preferably in the form of aqueous dispersions and more preferably in the form of water-redispersible powders.

It is preferred to adjust the amount of curing agent in the molar ratio of the monomer units a) of the modified water-soluble polymers and the functional groups of the curing agent, in particular the amino or epoxy groups of the curing agent. Accordingly, it is also particularly preferred that the modified water-soluble polymers and the curing agents in such Used ratio that the molar ratio of monomer units a) to the functional groups of the curing agent is from 0.5 to 2.0.

To prepare the hardener blends their individual components can be mixed in different ways. The hardeners can be introduced, for example, as pure substance or applied to carriers, such as calcium carbonate, silicates or zeolites, or in encapsulated form, for example in inorganic or organic encapsulating materials. The hardeners are preferably used as pure substance. For example, the hardeners, the modified water-soluble polymers, optionally the epoxide components and optionally the base polymers can each be mixed in solid form or in each case in aqueous form. Furthermore, it is also possible that one or more components of a hardener blend in solid form and remaining components in aqueous form are used for mixing. The hardeners and the further constituents of the hardener mixtures are preferably mixed only before they are applied, preferably immediately before their application. Particular preference is given to adding hardeners to aqueous dispersions comprising modified water-soluble polymers and epoxide components and / or base polymers, in particular protective-colloid-stabilized base polymers.

To improve the performance properties of the crosslinking agent composition, the polymer blends, blends with epoxy components or the hardener blends contain other additives such as fillers, pigments, plasticizers, foam stabilizers, flame retardants, water repellents, oils or other polymers, such as polyurethanes or polysiloxanes. Such additives may be present in amounts customary therefor, for example from 0.1 to 90% by weight, preferably from 2 to 50% by weight and more preferably from 2 to 10% by weight, based on the dry weight of the particular composition or mixdown. Most preferably, no additives are included.

For application as a crosslinking aid, the modified water-soluble polymers or the crosslinking agent composition, the polymer blends, the blends with epoxy components or the hardener blends are generally applied in liquid or pasty form, in particular as an aqueous mixture, to a substrate. The crosslinking generally occurs in the course of the filming of the polymers. Crosslinking is understood to mean that, in particular, monomer units a) of the modified water-soluble polymers react with polymers and any other constituents of the applied composition or the substrate, and form a network.

The crosslinking of the modified water-soluble polymers can advantageously be carried out at various temperatures, for example at 2 ° C. to 200 ° C., particularly preferably 15 ° C. to 160 ° C. If the crosslinking of the modified water-soluble polymers takes place in the absence of hardener, temperatures of 90 ° C. to 200 ° C. are preferred for this purpose, and 130 ° C. to 160 ° C. are particularly preferred. Crosslinking at temperatures below 30 ° C generally takes several days, for example one week. Above 100 ° C., in particular above 125 ° C., the crosslinking lasts for a few minutes, for example 1 to 10, in particular 2 to 5 minutes.

The crosslinking agents of the present invention can be used in the typical applications thereof and are generally useful as crosslinking agents for coatings or adhesives, such as woven or non-woven fabrics, fibers or paper. Particularly preferred is the use as a crosslinking agent for the production of paper coatings, in particular for thermal and inkjet papers, or for the coating of inorganic and organic fibers.

Further possible applications for the modified water-soluble polymers are in construction-chemical products, if appropriate in connection with mineral binders such as cements (Portland, aluminate, trass, metallurgical, magnesia, phosphate cement), gypsum and waterglass, for the production of construction adhesives, in particular tile adhesives and full heat protection adhesives, plasters, fillers, floor fillers, leveling compounds, sealing slurries , Grout, primer, water vapor barriers and paints.

The modified water-soluble polymers according to the invention, after crosslinking, surprisingly lead to products with soil-repelling properties and with the desired water resistance. In connection with this, the extractability of water-soluble constituents from the crosslinked products is correspondingly reduced, which counteracts the occurrence of efflorescence. Crosslinked modified water-soluble polymers are characterized by a very low water absorption. The modified water-soluble polymers are speck-free, shear and storage stable, redispersible in water in the uncrosslinked state and water-resistant after crosslinking. When using the modified water-soluble polymers according to the invention as crosslinking aids, it is advantageously possible to dispense with harmful curing agents, such as formaldehyde-releasing hardeners.

The following examples serve to further explain the invention:

Preparation of the modified water-soluble polymers Solids content:

Determination according to DIN EN ISO 3251 in a drying cabinet for 20 min at 150 ° C

Hoppler viscosity:

Determination at 20 ° C according to DIN 53015 in 4% aqueous solution.

Brookfield viscosity:

Determined with a Brookfield viscometer, after tempering at 23 ° C, using spindle 1 or 2 at 20 revolutions per minute. The individual spindle, solvent and solids content are given for each measurement.

Volume average particle size:

Determination using Beckman Coulter BeckmanCoulter LS 13320 (PIDS).

Example 1 (Ex.1):

In a 3.0 liter thermostatted laboratory reactor, under a nitrogen atmosphere, 1002 g of a 20% polyvinyl alcohol aqueous solution (Mowiol 4-88, trade name of Kuraray, Höppler viscosity 4 mPas, degree of saponification 88) and 1196 g of water were mixed with 1.1 g Submitted potassium peroxodisulfate (KPS) and heated to 80 ° C with stirring. When reaching 80 ° C, a monomer mixture of 113 g of butyl acrylate and 113 g of styrene was added continuously within 70 minutes in the reactor. After dosing the monomer mixture, 75.3 g of glycidyl methacrylate (GMA) were continuously added to the reactor from a separate container over 30 minutes. After GMA dosing, the resulting reaction mixture was cooled to room temperature over one hour. During the cooling phase, 4 g of tert-butyl hydroperoxide (10% strength in water) and 4 g of ascorbic acid (10% strength in water) were added twice for postpolymerization.

The polymer dispersion thus obtained had a solids content of 20.2%, at pH 7 a Brookfield viscosity of 147 mPa.s (spindle 1) and a volume-average particle size of 87 nm.

Example 2 (example 2):

In a thermostatted laboratory reactor with a filling volume of 3.0 liters, 752 g of a 20% strength aqueous polyvinyl alcohol solution (Mowiol 4-88) and 1396 g of water were introduced under a nitrogen atmosphere submitted with 0.8 g of potassium peroxodisulfate (KPS) and heated to 80 ° C with stirring. Upon reaching 80 ° C, a monomer mixture of 137.8 g of butyl acrylate and 137.8 g of styrene was added continuously within 85 minutes in the reactor. After dosing, 75.3 g of glycidyl methacrylate (GMA) were continuously added to the reactor from a separate container within 30 minutes. After GMA dosing, the resulting reaction mixture was cooled to room temperature over one hour. During the cooling phase, 4 g of tert-butyl hydroperoxide (10% in water) and 4 g of ascorbic acid (10% in water) were added twice for post-polymerization.

The polymer dispersion thus obtained had a solids content of 20.1%, at pH 7 a Brookfield viscosity (spindle 1) of 56 mPa.s and a volume-average particle size of 80 nm.

Example 3 (example 3):

In a thermostatically controlled laboratory reactor with a filling volume of 3.0 liters, 1002 g of a 20% strength aqueous polyvinyl alcohol solution (Mowiol 4-88) and 1196 g of water with 1.1 g of potassium peroxodisulfate (KPS) were initially charged under nitrogen and the mixture was heated to 80.degree heated. Upon reaching 80 ° C, a monomer mixture of 144.5 g of butyl acrylate, 144.5 g of styrene and 15 g of vinyltriethoxysilane was added continuously within 70 minutes in the reactor. After dosing, the polymerization was continued for one hour. Thereafter, the resulting reaction mixture was cooled to room temperature within one hour. During the cooling phase, 4 g of tert-butyl hydroperoxide (10% strength in water) and 4 g of ascorbic acid (10% strength in water) were added twice for postpolymerization.

The polymer dispersion thus obtained had a solids content of 20.1%, at pH 5 a Brookfield viscosity of 160 mPa.s (spindle 1) and a volume-average particle size of 89 nm.

Comparative Example 4 (VBsp.4):

In a thermostatted laboratory reactor with a filling volume of 3.0 liters, 502.6 g of a 20% aqueous polyvinyl alcohol solution (Mowiol 4-88) and 1595 g of water with 0.8 g of potassium peroxodisulfate (KPS) were initially charged under nitrogen and the mixture was brought to 80 with stirring ° C heated. Upon reaching 80 ° C, a monomer mixture of 137.8 g of butyl acrylate and 137.8 g of styrene was added continuously within 85 minutes in the reactor. After dosing the monomer mixture, 75.3 g of glycidyl methacrylate (GMA) were continuously added to the reactor from a separate container over 30 minutes. After GMA dosing, the resulting reaction mixture was cooled to room temperature over one hour. During the cooling phase, 4 g of tert-butyl hydroperoxide (10% strength in water) and 4 g of ascorbic acid (10% strength in water) were added twice for postpolymerization.

The polymer dispersion thus obtained had a solids content of 20.3%, at pH 7 a Brookfield viscosity of 32 mPa.s (spindle 1) and a volume-average particle size of 110 nm.

Testing the redispersion behavior of polymer films based on modified water-soluble polymers:

• 24h RT:
  • Trocknung für 24 Stunden unter Normalbedingungen nach DIN50014;
• 24h RT, 3 min 150°C:
  • Trocknung für 24 Stunden unter Normalbedingungen nach DIN50014; anschließend zusätzlich für 3 Minuten im Trockenschrank bei 150°C.

The dispersions of the (comparative) examples were each applied to a glass plate; after application of the following drying conditions, polymer films were obtained with layer thicknesses of 0.2 mm:

• 24h RT:
  • Drying for 24 hours under normal conditions according to DIN50014;
• 24h RT, 3 min 150 ° C:
  • Drying for 24 hours under normal conditions according to DIN50014; then additionally for 3 minutes in a drying oven at 150 ° C.

To check the redispersibility of the polymer films thus obtained, a drop of water was used in each case with a pipette was applied to a homogeneous point of the polymer film to be tested under normal conditions according to DIN50014, and after 60 seconds exposure time of the water droplet was rubbed with the fingertip in the same place until the film was redispersed either in water at this point or if no redispersion occurred until the film fell into pieces of film.

• Note 1: Film lässt sich durch leichtes Reiben sofort redispergieren oder redispergiert bereits selbständig;
• Note 2: Film lässt sich durch Reiben redispergieren;
• Note 3: Film lässt sich nur durch kräftiges Reiben teilweise redispergieren; es verbleiben nicht redispergierbare Filmstücke;
• Note 4: Film lässt sich selbst durch längeres kräftiges Reiben nicht redispergieren, sondern zerfällt in Filmstücke.

Tabelle 1: Redispergierbarkeit der Polymerfilme von modifizierten wasserlöslichen Polymeren: Polymer PVOH-Anteil^a) Redispergierbarkeit der Polymerfilme 24h RT 24h RT, 3 min 150°C Bsp.1 40% 1 4 Bsp.2 30% 2 4 Bsp.3 40% 1 3 VBsp.4 20% 4 4 a) Anteil von Polyvinylalkohol in Gew.-%, bezogen auf das Trockengewicht des modifizierten wasserlöslichen Polymers. The redispersibility of the polymer films was evaluated by the following evaluation scheme:

• Grade 1: Film can be readily redispersed by light rubbing or already redispersed independently;
• Grade 2: Film can be redispersed by rubbing;
• Grade 3: Film can be partially redispersed only by vigorous rubbing; it remains not redispersible film pieces;
• Note 4: Film can not be redispersed even by prolonged vigorous rubbing, but decays into pieces of film.

Table 1: Redispersibility of the polymer films of modified water-soluble polymers: polymer PVOH content ^a) Redispersibility of the polymer films 24h RT 24h RT, 3 min 150 ° C Ex.1 40% 1 4 Ex.2 30% 2 4 EX3 40% 1 3 VBsp.4 20% 4 4 a) proportion of polyvinyl alcohol in wt .-%, based on the dry weight of the modified water-soluble polymer.

The test shows that polymer films of polymers according to the invention which are dried for one day at room temperature can easily be absorbed again in water at room temperature, in contrast to the polymer film of Comparative Example 4. However, if the polymer films were dried at elevated temperature, the polymer films according to the invention were in spite of their high proportion of water-soluble polymers in any appreciable extent in water absorbable.

Testing the redispersion behavior of polymer films based on modified water-soluble polymers and hardeners:

• 1w RT:
  • Trocknung für 1 Woche unter Normalbedingungen nach DIN 50014;
• 1w RT, 3 min 150°C:
  • Trocknung für 1 Woche unter Normalbedingungen nach DIN 50014; anschließend zusätzlich für 3 Minuten im Trockenschrank bei 150°C.

50 g each of the respective polymer dispersion of the (comparative) Examples were mixed with the amounts indicated in Table 2 on the particular curing agent under standard conditions according to DIN50014. Subsequently, the mixtures thus obtained were each applied to a glass plate; after application of the following drying conditions, polymer films were obtained with layer thicknesses of 0.2 mm:

• 1w RT:
  • Drying for 1 week under normal conditions according to DIN 50014;
• 1w RT, 3 min 150 ° C:
  • Drying for 1 week under normal conditions according to DIN 50014; then additionally for 3 minutes in a drying oven at 150 ° C.

The redispersibility of the polymer films thus obtained was evaluated according to the scheme defined above with the grades 1 to 4. The test results are summarized in Table 2. Table 2: Redispersibility of the polymer films of modified water-soluble polymers and hardeners: polymer Harder Redispersibility of the polymer film 1w RT 1w RT, 3 min 150 ° C Ex.1 1.2 g of Jeffamine T-403 ^a) 4 4 EX3 0.3 g of silane GF 82 ^b ) 1 - 2 3 - 4 a) polyetheramine from Huntsman;
b) (3-glycidoxypropyl) triethoxysilane) from Wacker Chemie.

Hardeners generally lead to a stronger or faster crosslinking of the modified water-soluble polymers. The Examination results with the polymer of Example 1 and Jeffamine T-403 show that water-resistant polymer films can be obtained even after drying at room temperature by additionally using a hardener.

Preparation of a Polymer Dispersion (Base Polymer):

In a polymerization vessel with 12 liters volume 2230 g of water, 2380 g of a 20% aqueous solution of a polyvinyl alcohol having a degree of hydrolysis of 88 mol% and a Höppler viscosity of 4 mPas, 10 g of iron ammonium sulfate (1% in Water) and 1050 g of butyl acrylate and 617 g of styrene and heated to 70 ° C. Subsequently, tert-butyl hydroperoxide (0.1% strength in water) and Brüggolit (sodium hydroxymethanesulfinate, 0.15% strength in water) were metered in continuously at a metering rate of 10 g / h each. From the beginning of the polymerization, recognizable by the increase in the internal temperature, the remaining monomer mixture comprising 1950 g of butyl acrylate and 1150 g of styrene was added continuously in 3.5 hours at a metering rate of 885 g / h. Three hours after the start of the polymerization, the metering rate of the initiator was continuously increased within 1 hour to 60 g / h. It was polymerized until no heat of polymerization was released. To remove residual monomers, after cooling to 30 ° C., 10 g of tert-butyl hydroperoxide (10% strength in water) and 20 g of Brüggolit (10% strength in water) were postpolymerized.

A dispersion having a solids content of 53.7%, a Brookfield viscosity (spindle 2) of 680 mPas, a pH of 4.3 and a particle size diameter Dw of 800 nm was obtained. After sieving with a sieve with a mesh size of 250 μm, 2 g of sieve residue were obtained. The free residual monomer was <100 ppm.

Production of polymer powders: Comparison powder 1 (VPulver 1):

90% by weight of the dispersion of the base polymer was admixed with 10% by weight (solid / solid) polyvinyl alcohol Mowiol 4/88 having a degree of hydrolysis of 88 mol% and a Höppler viscosity of 4 mPas, and with water to a Hoppler viscosity of 250 mPas diluted. The dispersion was then sprayed by means of a two-component nozzle. As Verdüsungskomponente served to 4 bar pre-compressed air, the droplets formed were dried with heated to 125 ° C air in the DC. The dry powder obtained was mixed with 10% by weight of commercially available antiblocking agent (mixture of calcium magnesium carbonate and magnesium hydrosilicate).

Comparison powder 2 (VPulver 2):

Identical as VPulver 1, with the difference that 80 wt .-% dispersion of the base polymer (solid / solid) used and the dispersion additionally 10 wt .-% Epilox P 13-31 (triglycidyl ether based on trimethylolpropane from Leuna-resins) were added.

Powder 3:

Same as VPulver 1, with the difference that instead of the polyvinyl alcohol Mowiol 4/88 the appropriate amount (solid / solid) were used on the modified water-soluble polymer of Example 1.

Powder 4:

Identical as powder 3, with the difference that 80 wt .-% dispersion of the base polymer (solid / solid) and the dispersion additionally added 10 wt .-% Epilox P 13-31 (triglycidyl ether based on trimethylolpropane from Leuna resins) were.

Testing the strength of films of polymer powders: Determination of tensile strength:

50 g each of the (comparative) powders were converted into redispersions having a solids content of 50% by adding water. The respective redispersion was optionally mixed with the Jeffamine T-403 hardener, in the amount as indicated in Table 3. A portion of the respective redispersion was applied to a glass plate and dried for one week under normal conditions to DIN50014, whereby a polymer film having a layer thickness of 0.2 mm was obtained.

The respective polymer film was then stored for three days at 21 ° C in water and then tested in a tensile test according to DIN 5304. The results of the testing are shown in Table 3.

Determination of the contamination resistance test:

• +++ Fleck nicht sichtbar;
• ++ Fleck kaum erkennbar;
• - Fleck sichtbar.

Polymer films were prepared as described under heading "Determination of Tear Resistance". Coffee or currant juice was dripped onto the respective dried polymer film and then stored overnight under normal conditions (DIN 50014 23/50). Thereafter, the polymer films were washed with 23 ° C warm water and visually evaluated as follows:

• +++ stain not visible;
• ++ spot hardly recognizable;
• - stain visible.

The results are summarized in Table 3.

Stability filled moldings:

• stabil: der Formkörper verblieb nach Wasserlagerung dimensionsstabil;
• zerfallen: Formkörper nach Wasserlagerung in Bruchstücke zerfallen.
• Die Ergebnisse der Austestung sind in folgender Tabelle in der Spalte "Stabilität" aufgelistet.

50 g of the respective (comparative) powder were mixed with sand (BCS 413, average particle size 130 micrometers) in a weight ratio of 1: 2 and mixed with the amount of hardener indicated in Table 3. Subsequently, water was added and mixed, whereby the (comparative) powders were redispersed. The molding compositions thus obtained were placed in a mold (length / width / height = 10 cm / 1 cm / 4 mm) and dried. The moldings thus obtained were in water at room temperature stored and assessed the stability after 7 days as follows:

• stable: the molded body remained dimensionally stable after storage in water;
• disintegrate: shaped bodies disintegrate into fragments after storage in water.
• The results of the testing are listed in the following table in the column "Stability".

Comparative powder 1 without addition of hardener gave the worst results (Table 3). When the corresponding powder was modified with an epoxy compound and an amine hardener, the tear strength of the polymer film and the stability of the molding compound were improved, but further, no soiling resistance test was achieved (Table 3: VPulver 2). The powders 3 and 4 according to the invention led to molding compositions having the desired tensile strength and stability and, moreover, to contamination-resistant shaped bodies. Table 3: Testing of polymer films based on modified water-soluble polymers, base polymers and optionally hardeners: powder Hardener * [g] Tear resistance [Mpa] stability fouling resistance coffee Currant juice VPulver 1 - 7.1 decay - - VPulver 2 3.0 9.2 stable - - Powder 3 0.8 8.2 stable ++ ++ Powder 4 3.0 10.5 stable +++ +++ *: Jeffamine T-403: polyetheramine from Huntsman.

Claims (13)

1. Use of modified water-soluble polymers as crosslinking agents, characterized in that said modified water-soluble polymers are obtainable by free-radically initiated polymerization of

   a) one or more ethylenically unsaturated monomers bearing one or more epoxy, amine, carboxylic acid, carboxylic anhydride and/or silane groups, and

   b) one or more ethylenically unsaturated monomers other than said monomers a) in the presence of 25 to 80 wt% of one or more water-soluble polymers, based on the overall weight of modified water-soluble polymers.
2. Use of modified water-soluble polymers as crosslinking agents according to Claim 1, characterized in that one or more monomers a) are selected from the group comprising glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether; 2-dimethylaminoethyl methacrylate, 2-tert-butylaminoethyl methacrylate, allyl N-(2-aminoethyl)carbamate hydrochloride, allyl N-(6-aminohexyl)carbamate hydrochloride, allyl N-(3-aminopropyl) hydrochloride, allylamine or vinylpyridine; acrylic acid, methacrylic acid, fumaric acid and maleic acid; monoesters of fumaric acid; monoesters of maleic acid and maleic anhydride.
3. Use of modified water-soluble polymers as crosslinking agents according to Claim 1, characterized in that one or more monomers a) are selected from the group comprising ethylenically unsaturated silicon compounds of general formula R¹SiR² _0-2(OR³)_1-3, where R¹ is CH₂=CR⁴-(CH₂)_0-1 or CH₂=CR⁴CO₂(CH₂)_1-3, R² is C₁-C₃ alkyl, C₁-C₃ alkoxy or halogen, R³ is branched or unbranched, optionally substituted alkyl of 1 to 12 carbon atoms or acyl of 2 to 12 carbon atoms, wherein R³ may optionally be interrupted by an ether group, and R⁴ is H or CH₃; and
   silane group-containing (meth)acrylamides of general formula CH₂=CR⁵-CO-NR⁶-R⁷-SiR⁸n-(R⁹)_3-m, where n = 0 to 4, m= 0 to 2, R⁵ is either H or methyl, R⁶ is H or alkyl of 1 to 5 carbon atoms; R⁷ is alkylene of 1 to 5 carbon atoms or a bivalent organic group in which the carbon chain is interrupted by an oxygen or nitrogen atom, R⁸ is alkyl of 1 to 5 carbon atoms, R⁹ is alkoxy of 1 to 40 carbon atoms, which may each be substituted with further heterocycles.
4. Use of modified water-soluble polymers as crosslinking agents according to Claim 1 or 2 or 3, characterized in that said monomers a) are employed in an amount of 0.5 to 60 wt%, based on the overall weight of the modified water-soluble polymers.
5. Use of modified water-soluble polymers as crosslinking agents according to Claim 1 or 2 or 3 or 4, characterized in that one or more monomers b) are selected from the group comprising vinyl esters, (meth)acrylic esters, vinylaromatics, olefins, 1,3-dienes and vinyl halides.
6. Use of modified water-soluble polymers as crosslinking agents according to Claim 1 or 2 or 3 or 4 or 5, characterized in that said monomers b) are employed in an amount of 5 to 73 wt%, based on the overall weight of the modified water-soluble polymers.
7. Use of modified water-soluble polymers as crosslinking agents according to Claim 1 or 2 or 3 or 4 or 5 or 6, characterized in that one or more water-soluble polymers are selected from the group comprising proteins, ligninsulfonates, formaldehydesulfonates, polysaccharides in water-soluble form and also polymers containing one or more units from the group comprising vinyl alcohol units, vinylpyrrolidone units, vinyl acetal units, vinylsulfonic acid units, acrylamide units and/or units of ethylenically unsaturated carboxylic acids and/or ethylenically unsaturated amines or ammonium compounds.
8. Use of modified water-soluble polymers as crosslinking agents according to Claim 1 or 2 or 3 or 4 or 5 or 6 or 7, characterized in that one or more water-soluble polymers are selected from the group comprising polyvinyl alcohols; polyvinyl acetals; polyvinylpyrrolidones; polysaccharides in water-soluble form such as starches (amylose and amylopectin), celluloses and their carboxymethyl, methyl, hydroxyethyl and/or hydroxypropyl derivatives, dextrins and cyclodextrins; proteins such as casein or caseinate, soyprotein, gelatin; ligninsulfonates; synthetic polymers such as poly(meth)acrylic acid, copolymers of (meth)acrylates with carboxyl-functional comonomer units, poly(meth)acrylamide, polyvinylsulfonic acids and their water-soluble copolymers; melamineformaldehydesulfonates, naphthaleneformaldehydesulfonates, cresolformaldehydesulfonates, styrene-maleic acid copolymers and vinyl ether-maleic acid copolymers.
9. Use of modified water-soluble polymers as crosslinking agents according to Claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8, characterized in that the polymerization is initiated with one or more initiators and ≥ 20 wt% of initiators, based on the overall weight of all the initiators used in the polymerization, is initially charged before initiation of the polymerization and the remaining portion of the initiators is metered in during the polymerization.
10. Use of modified water-soluble polymers as crosslinking agents according to Claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9, characterized in that at least 50 wt% of the water-soluble polymers is initially charged before initiation of the polymerization, based on the total amount employed of water-soluble polymers.
11. Use of modified water-soluble polymers as crosslinking agents according to Claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10, characterized in that from 0 to 20 wt% of said monomers a) and b), based on the overall amount of the altogether employed amounts of monomers a) and b), is initially charged before initiation of the polymerization and the remainder of monomers a) and b) is metered in during the polymerization.
12. Use of modified water-soluble polymers as crosslinking agents according to Claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11, characterized in that one or more modified water-soluble polymers are present as a constituent of a crosslinking agent composition additionally containing one or more components from the group comprising base polymers, epoxy components, hardeners and additives.
13. Use of modified water-soluble polymers as crosslinking agents according to Claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12, characterized in that the crosslinking agents are employed in chemical products used in civil engineering, in coatings or adhesives, in particular for woven or nonwoven textiles, paper or fibers.